Method of preparing a solution of cellulose



Patented Aug. 19, 1941 METHOD oF PREPARING A SOLUTION F oELLULosE EricOwen Ridgway, Montclair, and William A. Bodenschatz, Brooklawn, N. J.,assignors to Ridbo Laboratories Incorporated, Nutley, N. J a corporationof New'Jcrsey No Drawing. Original application November 1,

1937, Serial No. 172,152. Divided and this application August 17, 1939,Serial No.-290,626

4 Claims.

This invention relates to a method of preparing a solution of cellulosehaving a low ammonia content for the production of rayon.

The invention further contemplates the manufacture-of a completesolution of cellulose which may be employed in the manufacture of rayonor stable fibre for the production of spun rayon, or coating fabrics orfor other uses.

This application is a divisional application of our copendingapplication Serial No. 172,152, filed November 1, 1937.

In accordance with the present invention, the improved method ofpreparing a solution of cellulose having a low ammonia content forproduction of rayon comprises wetting the cellulose in a solution of awater-soluble copper salt, and adding a solution of ammonium hydroxideand an alkaline hydroxide, the reaction being carried out at a lowtemperature.

The object of the present invention is to produce a solution of ellulosewhich will have the desired low ammonia concentration necessary for theeconomical spinning of copper ammonia rayon.

The cellulose concentration of the solution made according to the methodof the present invention is adequate for modern spinning practicesemploying either prepared linters or prepared wood pulp as a source ofcellulose and may range up to approximately eight per cent cellulose.

A feature of the invention is the treatment of cellulosic fibres in sucha manner that a substantially complete solution of cellulose is obtainedand having a very low ammonia content,

such that the solution may be spun in a dilute alkali solution andWashed with acid and then water, and dried, for the production of spunrayon. The solution of cellulose may, of course, be spun according toany other methods of spinning known in the art.

For example a suitable cellulosic material of known alpha-cellulosecontent is wetted with a solution of any water-soluble copper salt.Satisfactory results have been obtained by employing copper sulphate,copper nitrate, copper bromide, or copper chloride. The concentration ofthe copper salt solution is governed by the concentration of cellulosedesired in the final solution, that is, a higher cellulose concentrationin a finished solution requires a more concentrated copper saltsolution. The copper to cellulose ra tio and the ammonia to copper ratioare constant, and therefore the variable is the concentration of thecopper salt solution.

A satisfactory solution of cellulose can be obtained by wetting thecellulose ina solution of copper sulphate of a concentration of from 100to 400 grams of copper sulphate per litre and then dissolving thecellulose by slowly adding a solution of ammonium hydroxide and sodiumhydroxide of a concentration of from to 117.6 grams of ammonia per litreand from 15 to 94.08 grams of sodium hydroxide per litre, thetemperature of the solution being maintained in the neighborhood of 4centigrade.

The present invention will be readily understood from the followingspecific example in which the preferred method of employing theinvention is given.

369.41 cc. of a copper sulphate solution containing 58.37 grams ofCllSOI-I2O are added to 38 grams of dry alpha cellulose such as lintersor pulp. After the pulp or linters have been completely opened up andwetted by mixing, 630.59 cc. of a solution containing 28 grams of NH3and 13.7 grams of NaOH are added. This last solution is added slowly andat a low temperature, for example 4 centigrade; the dissolution of thecellulose takes place more rapidly and completely at a low temperature.Cracked ice may be substituted in part for water to bring the finalvolume to one litre.

The solution of cellulose is spun in a dilute alkali solution and washedwith acid and then with water and finally dried for the production ofspun rayon.

It will be seen that in practice more accurate control of the reactingingredients is obtained by our improved method in which the materialbeing treated is first wetted with a copper salt solution before theingredients reacting with the copper salt solution and the cellulose areintroduced.

It is to be understood that the foregoing example setting forth specificmaterials, weights and proportions, is given for the purpose only ofillustrating the invention, and that our invention is not limitedthereto but contemplates such other and further modifications andchanges which may become apparent to those skilled in the art.

We claim:

1. The method of preparing a solution of cellulose having a low ammoniacontent for the production of rayon, which comprises wetting the saidcellulose in a solution of copper sulphate of a concentration of from to400 grams of copper sulphate per litre, dissolving said cellulose byslowly adding a solution containing ammonium hydroxide in aconcentration of from 25 to 117.6 grams of ammonia per litre and sodiumhydroxide of a concentration of from 15 to 94.08 grams of sodiumhydroxide per litre and maintaining the temperature of the resultingsolution in the neighborhood of 4 centigrade, said reagents beingpresent in the solutions in approximate proportions of 1.54 parts ofcopper sulphate (CllSO45H2O) to 1 partof cellulose, 3.13 parts of coppersulphate (CuSO45I-IzO) to 1 part of sodium hydroxide, and at least 1.5parts of ammonia to 1 part of sodium hydroxide.

2. The method of preparing a solution of cellulose having a low ammoniacontent, which comprises Wetting said cellulose in a solution ofwater-soluble copper salt selected from the class consisting of coppersulphate, copper nitrate, copper bromide and copper chloride, and addinga solution of ammonium of hydroxide of at least 25 grams ammonia perlitre and an inorganic alkaline hydroxide, the reaction being carriedout ata low temperature.

3. The method of preparing a solution of cellulose having a lowammoniacontent for the production of rayon, Which comprises Wetting saidcellulose in a solution of copper sulphate,

and then adding to said wetted cellulose a solution of ammoniumhydroxide and sodium hydroxide, the reaction being carried out at a lowtemperature and said reagents being present in the solutions inapproximate proportions of 1.5 parts of ammonia to 1 part of sodiumhydroxide, 3.13 parts of copper sulphate (CuSO45H2O) to 1 part of sodiumhydroxide, and 1.54 parts of copper sulphate (CuSOrSHzO) to 1 part ofcellulose.

4. The method of preparing a solution of cellulose having a low ammoniacontent for the production of rayon, which comprises wetting thecellulosic material in a solution of copper sulphate, and then adding tothe wetted material a solution of ammonium hydroxide and sodiumhydroxide, the reaction being carried out at a low temperature and insolutions containing approximately 5837 grams of copper sulphate(CuSO45I-I2O) in a 369.41 cc. solution, and 28 grams of ammonia and 18.7grams of sodium hydroxide in a 630.59 cc. solution for each 38 grams ofcellulosic material being treated.

WILLIAM A. BODENSCHATZ. ERIC OWEN RIDGWAY.

. eolumn, line 19,' c1aim 2, for ammonium of hydroxide" read-8.1mn0n111.m

I-ection therein that the same may conform to the vrecord ofthe case inthe CERTIFICATE 6F coRREcTIofi. Patent No. 2,252,751. u st 19, 19!;1.

} ERIC OWEN RIDGWAY, ET AL. It is. hereby certified that error ap pearsin the printed specification of the abovern'umbered patent requiringeorrectien as follows: Page 2, 'first hydroxide-q and that the saidLetters Patent should be readwith this 0011" Patent Office. I

Sign'edend sealed this 7th day of October, A. D. 191m.

, Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

